Polyetherimide ester elastomers comprised of the reaction products of (a) a low molecular weight diol, (b) a dicarboxylic acid, (c) a high molecular weight poly(oxy alkylene)diamine, and (d) a tricarboxylic acid or its derivative. along with processes for their preparation, are described in U.S. Pat. Nos. 4,544,734 and 4,556,705 to McCready and in U.S. Pat. No. 4,556,688 to McCready et al. These poly (etherimide ester) elastomers exhibit excellent stress-strain properties, low tensile set, high melting temperatures and/or excellent strength/toughness characteristics as well as superior flexibility, which properties render them especially suitable for molding and extrusion applications. These polymers are usually produced by melt condensation or solution condensation processes. While these processes are generally quite effective in producing polyetherimide ester polymers, they nevertheless suffer from several problems or disadvantages when utilized in the preparation of very high molecular weight polyetherimide ester polymers. These disadvantages include thermal degradation of the very high molecular weight polymer, economic penalties associated with the production of high molecular weight polymers, and some discoloration of the resultant high molecular weight polymer.
It has now been discovered that polyetherimide ester polymers, particularly very high molecular weight polyetherimide ester polymers, can be effectively and efficiently produced by the utilization of a solid phase polycondensation process.